Curing agents for epoxy resins

Abstract

A curable composition comprising an epoxy resin or a monoepoxide and a curing agent comprising a metal salt complex of an adduct of an imidazole and a monofunctional epoxy compound.

I claim: 
     
       1. A curable composition comprising an epoxy resin or a monoepoxide and a curing agent comprising a metal salt complex of an adduct of an imidazole and a monofunctional epoxy compound. 
     
     
       2. A composition as claimed in claim 1 and wherein the adduct is formed from imidazole or 2-ethyl-4-methylimidazole. 
     
     
       3. A composition as claimed in claim 1 and wherein the adduct is formed from an epoxy compound containing up to 20 carbon atoms. 
     
     
       4. A composition as claimed in claim 3 and wherein the epoxy compound is a glycidyl ether. 
     
     
       5. A composition as claimed in claim 4 and wherein the epoxy compound is phenylglycidyl ether. 
     
     
       6. A composition as claimed in claim 1 and wherein the molar ratio of the imidazole to epoxy used in the formation of the adduct is 1:1 or 1:2. 
     
     
       7. A composition as claimed in claim 1 and wherein the metal salt used in the formation of the complex is selected from CuCl 2 , CuBr 2 , Cu(NO 3 ) 2 , copper acetate, copper propionate, CaCl 2 , CoCl 2 , ZnCl 2  and cadmium acetate. 
     
     
       8. A composition as claimed in claim 1 and wherein the metal salt to adduct molar ratio used in the formation of the complex is between 1:1 and 1:6. 
     
     
       9. A composition as claimed in claim 1 and wherein the curing agent additionally comprises at least one nitrogenous compound. 
     
     
       10. A composition as claimed in claim 9 and wherein the curing agent additionally comprises at least one aromatic polyamine. 
     
     
       11. A composition as claimed in claim 1 and wherein the ratio of the complex to the epoxy resin or monoepoxide is from 0.5 to 40 parts weight of the complex to each 100 parts by weight of the epoxy resin or monoepoxide. 
     
     
       12. A complex suitable for use in or as the curing agent in the composition specified in claim 1 the complex being a complex of a metal salt and an adduct of an imidazole with a monofunctional epoxy compound having not more than 20 carbon atoms. 
     
     
       13. A complex as claimed in claim 12 and wherein the said epoxy compound is a glycidyl ether. 
     
     
       14. A complex as claimed in claim 14 and wherein the said epoxy compound is phenylglycidyl ether. 
     
     
       15. A complex as claimed in claim 14 and wherein the imidazole is selected from imidazole and 2-ethyl-4-methylimidazole.